Fendlera is treated as having five closely related species, four of which have been recognized by previous authors, and F. tamaulipana B. L. Turner, sp. nov., a newly described taxon from northeastern Mexico. Except for the latter, the species are all to some extent sympatric but their populations are relatively uniform and their diagnostic characters do not suggest that intergradation in a populational sense occurs. The taxa do not normally occur together, although they may occur in close proximity and probably do occasionally hybridize, this perhaps confounding taxonomic interpretations of the genus by previous workers. The five species recognized are: F. rupicola, so far as known, confined to three small populations in central Texas; F. falcata, occurring in northwestern Mexico and the southwestern United States; F. wrightii, having a distribution similar to that of the foregoing; F. linearis (including F. rigida), occurring mostly in northeastern Mexico and closely adjacent Trans-Pecos, Texas; and the newly described, F. tamaulipana, known by three collections from the vicinity of Miquihuana, Tamaulipas, Mexico. Distribution maps are provided for all of the species concerned.

Two very different systems of classification of the family Polemoniaceae—one a taxonomic system and the other a molecular cladistic system—have appeared recently. They are compared and reviewed. It is emphasized that taxonomy and cladistics use different basic systematic units (taxa or clades) and have different concepts of monophyly. Furthermore, taxonomy and molecular cladistics differ in the characters used in classification. Conflicts between molecular and reliable morphological characters occur in several parts of the family. The differences in methodology account for most of the incongruences between the two classifications of the family. In general, the methodological differences can be expected to yield incongruences between taxonomic and cladistic systems in any heterogeneous group of medium or large size. New suggestions are made about the early phylogenetic divergences in the Polemoniaceae. The tribes are reviewed from a taxonomic standpoint and a few changes are made.

The task of finding the correct names for the main subdivisions of Phlox has been beset with difficulties in interpreting the intent of older authors, particularly Asa Gray. Gray divided Phlox into four main subgroups, some of which have been considered sections, but these are now seen to be only informal groups. Currently Phlox is subdivided into three sections: Phlox, Divaricatae Peter, and Occidentales A. Gray. The name Occidentales A. Gray was not validly published as a section; Gray used it only as part of a heading. The oldest valid name for what has been called sect. Occidentales is sect. Pulvinatae Peter. Recent papers have used the name sect. Annuae A. Gray in place of sect. Divaricatae, on grounds of priority. However, the name that Gray actually used was Annuae, Texenses, and it, like Occidentales, was not validly published. The sections of Phlox are being reconsidered at present in the light of new molecular evidence. Some changes will be needed, but old valid infrageneric names will still have a role to play in new infrageneric classifications.

Nemophila sayersensis, a cryptic species restricted to sandy, nutrient poor soils and sister to N. phacelioides, is described and illustrated. While examining type material of N. phacelioides and that of its synonyms, it became obvious that the species had never been typified despite its widespread distribution and treatment in numerous revisions. We here typify all named entities associated with the two species.

Hymenoxys (Helenieae, Tetraneurinae) is composed of 28 taxa distributed in 8 subgenera: 1) subg. Hymenoxys, 2) subg. Dugaldia, 3) subg. Macdougalia, 4) subg. Phileozera, 5) subg. Picradenia, 6) subg. Picradeniella, 7) subg. Plummera, and 8) subg. Rydbergia. Eleven taxa comprise Hymenoxys subg. Picradenia.

A new species, Phyllanthus mutisianus, is described on the basis of a collection from Colombia made by the expedition of José Mutis. It is distinguishable from all other neotropical species of Phyllanthus by virtue of the distinctive leaf venation and very long fruiting pedicels. The type specimen lacks mature flowers, but the vegetative morphology, inflorescence, and fruiting structures suggest placement in subgenus Xylophylla, section Elutanthos.

A new species of Sida sect. Ellipticifoliae, Sida floridana, is described and accommodated in a revised key to the section. Additional notes are provided on selected taxa as an update to the most recent treatment.

Ipomoea series Tyrianthinae (House) D.F. Austin is revised in light of recent systematic surveys of New World morning glories. The group includes two species of vines and three highly derived shrubs. Four varieties of I. orizabensis (Ledeb.) Pelletan are recognized for the first time; two are new to science, I. orizabensis vars. austromexicana and novogaliciana, and one requires a new combination, I. orizabensis var. collina (House) J.A. McDonald. Molecular studies indicate that Ipomoea ser. Tyrianthinae shares close phylogenetic affinities with Ipomoea sects. Calonyction and Tricolores, yet few morphological features support this arrangement. It is assumed, therefore, that highly derived elements of the tyrianthina complex have undergone rapid morphological change in the arid environments of central and northern Mexico.